JP3023384B2 - Tensioning and adjusting device for chain device for camshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrapping type transmission in which one camshaft of an internal combustion engine drives a second camshaft and the relative rotational position of the camshaft can be changed by adjusting a chain. Chain) and tensioning devices.

[0002]

2. Description of the Related Art Such a tensioning and adjusting device is known from DE 34 210 28 A1. A tensioning device acts on a chain device wound around both camshafts of the internal combustion engine. The tensioning device consists of a hydraulic piston which tensions the tension and slack sides of the chain. Alternatively, two separate tensioning devices can act on the slack side and the tension side of the chain. In addition to the task of tensioning the chain, both devices have the purpose of changing the relative rotational position of the camshafts by extending the tension side and shortening the slack side or vice versa. As a result, the control time of the intake valve can be made variable, and the highest output and low exhaust emissions can be obtained over the entire rotational speed range of the internal combustion engine.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the tensioning and adjusting device in such a way that high operating safety is guaranteed at low cost.

[0004]

According to the invention, this object is achieved in that a first camshaft of an internal combustion engine drives a second camshaft by means of a helical transmission formed as a chain, and the second camshaft is moved transversely to the chain. Adjustment of the chain by a tensioning device acting in the direction changes the relative rotational position of the camshaft, this tensioning device slides transversely to the chain to adjust the chain, and the slack side of the chain is longer The tensioning device is formed such that the tensioning side is shortened or the slack side is shortened and the tensioning side is lengthened, and in the tensioning and adjusting device of the wrapping type transmission in which the tensioning device is hydraulically operable. The device comprises a hollow outer hydraulic piston, a hollow inner hydraulic piston guided in the hollow hydraulic piston, and a piston which is compressed and arranged in the hollow chamber between the two hydraulic pistons. In addition to the force of the coil compression spring, the hydraulic piston is continually biased hydraulically via a pressure connection between the two hydraulic pistons, and the outer hydraulic piston is The pressure can be alternately biased via the passage, which is solved by the fact that both hydraulic pistons are guided in the housing (18).

A tensioning device consisting of two hydraulic pistons and a spring which urges the hydraulic pistons in opposite directions and presses them against the chain is slid laterally with respect to the chain in order to adjust the chain. By doing so, when the functions are separated, the chain is always kept taut, irrespective of an emergency failure of the adjusting mechanism or its control mechanism. Even when the operation of the internal combustion engine is not optimal, the tension is maintained. In an advantageous embodiment of the invention, the tensioning and adjusting device comprises an outer hollow piston, an inner hollow piston guided longitudinally in this hollow piston, and a coil spring compressed centrally between the two pistons. And a hydraulic connection to the central hollow chamber. The outer piston has on its outer surface a second hydraulic connection. By biasing the hydraulic connection, the tensioning device can slide laterally with respect to the chain.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is shown in the drawing. Hereinafter, this embodiment will be described in detail.

An exhaust valve camshaft 2 for operating the exhaust valve is driven by a crankshaft 1 of the internal combustion engine via a toothed belt or chain. The exhaust valve camshaft 2 drives the intake valve camshaft 3 that controls the intake valve by a chain 4. A hydraulic tensioning device 7 acts on the tension side 5 and the loose side (return side) 6 of the chain 4 from inside the chain.

The tensioning device 7 comprises a hollow outer hydraulic piston 8
A hydraulic inner piston 9 which is also longitudinally guided in the hydraulic piston and has a coil compression spring 11 compressed in a hollow space 10 between the two hydraulic pistons. ing. In addition to the force of the coil compression spring 11, the hydraulic pistons 8, 9 are hydraulically urged by supplying hydraulic oil to the annular chamber 13 between the hydraulic pistons 8, 9 via the pressure connection 12. ing. A tension shoe 14 is fixed to the inner hydraulic piston 9. This tension shoe acts on the tension side 5 of the chain 4. A tension shoe 15 fixed to the end side inside the outer hydraulic piston 8 presses the loose side 6 of the chain 4. The outer hydraulic piston 8 has a collar 16 at the outer end. This collar is sealed in a bore 17 of the casing 18 and is guided longitudinally. A coil compression spring 20 is arranged between the collar 16 and a guide sleeve 19 fixed in a casing 18 in a compressed state. At this point, the hole 17 of the casing 18
Has a second pressure connection 21. Furthermore, a third pressure connection 22 is provided in the hole 17 on the end side of the hydraulic piston 8. The third pressure connection part 22 is connected to a casing hole 24 via a pressure passage 23. The second pressure connection portion 21 is connected to the casing hole via another pressure passage 25. On both end sides, return passages 26 and 27 open to the casing hole 24. A connection passage 28 is provided substantially at the center of the casing hole 24. This connection passage leads to a main passage 29 to which the pressure liquid is supplied from the pump. The first pressure connection 12 is constantly urged hydraulically from the main passage 29 via the pressure passage 30.

The pressure passages 23, 25 leading to the two pressure connections 21, 22 are alternately urged by hydraulic pressure. An adjusting slider 31 guided longitudinally in the housing bore 24 serves for this purpose. The control slide 32 opens and closes the opening 33 of the connecting passage 28 leading to the housing bore 24 by means of a control piston 32. In the position shown in FIG. 2, the hydraulic pressure reaches the pressure passage 25. The connection to the pressure passage 23 is prevented by a control piston 32 guided in a sealed manner in the housing bore 24. At the same time, the lower end of the casing hole is closed by the lower valve cylinder 34. When the second valve cylinder 35 exits from the upper end of the casing hole 24, the valve 36 between the pressure connection 22 and the return passage 26 opens.

In FIG. 3, conversely, the upper valve 36 is closed and the lower valve 37 is open. That is, the pressure passages 23 and 24 alternately function as pressure supply passages or return passages depending on the position of the adjustment slider 31.
Adjusting slider 3 axially pre-biased by spring 38
1 is slid axially by the electromagnet 39 to both switching positions.

If necessary, the pressure supply to the pressure passages 23, 25 can be switched continuously, so that the control piston 32 can occupy any intermediate position and the pressure supply to the pressure passages can be controlled. Can be performed in proportion to the parameter (characteristic value) of the internal combustion engine that controls the current supply to the electromagnet 39.

In order to avoid the unnecessarily high adjusting force generated in the case of a low-temperature and highly viscous pressure oil, the electromagnet is set to about 4 mm.
It is only switched on above the temperature of the internal combustion engine of 0 ° C.

The position of the collar 16 acting as an adjusting member can be detected by a sensor. The signal of this sensor is used as a test signal for the operation of the regulating device,
Alternatively, it can be used as a control variable for continuous adjustment of the chain. In the case of a defective adjusting function, the intake valve camshaft automatically reaches the relative rotational position which normally only occupies when the internal combustion engine is running idle.

For an internal combustion engine having two rows of cylinders, the tensioning and regulating device comprises one control part 40 and two tensioning and regulating parts 4 provided in both cylinder rows.
Dividing into 1 is advantageous for space and cost reasons. The control part 40 essentially comprises the main passage 29, the connection passage 28 and the valves 36, 37, as well as the adjusting slider 31 for controlling the valve with the electromagnet 39. The tensioning and adjusting part 41 comprises two hydraulic pistons 8, 9, pressure connections 12, 21, 22 and coil compression springs 11, 20.
Formed by

Instead of the camshaft driving device using the chain 4, a camshaft driving device using a toothed belt may be used.
The tensioning and adjusting device according to the invention acts on this toothed belt.

In FIGS. 1 to 3, the tensioning device acts on the inner surface of the chain 4. Alternatively, according to FIG. 4, the chain 4 can be stretched from its outer surface. In this case, the tensioning device 42 consists of two hydraulic pistons 43, 44 which are biased by pressure via passages 45, 46. At this time, the spring 47 between the hydraulic pistons 43 and 44 is tensioned.
A tension roller 48 is fixed to both hydraulic pistons 43 and 44. The chain 4 is stretched inward by the tension roller.

[0017]

As described above, the tensioning and adjusting device of the present invention separates functions by providing a chain tensioning device that slides in the lateral direction with respect to the chain in order to adjust the chain. The chain is always kept taut, irrespective of a possible failure of the adjusting mechanism or its control mechanism. Therefore, high driving safety is guaranteed at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view of a camshaft drive provided with a tensioning and adjusting device.

FIG. 2 is a cross-sectional view of the tensioning and adjusting device in a first position.

FIG. 3 is a cross-sectional view of the tensioning and adjusting device in a second position.

FIG. 4 is a view showing another embodiment of the tensioning device.

[Explanation of symbols]

 2,3 cam shaft 4 chain 5 tension side 6 slack side 7 tensioning device

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Alfred Chiyumiel, Germany, Grafenberg, Alpstraße, 9 (72) Inventor Wolfgang Schyutefan Germany, Twitzeishausen, Lerchienstraße , 10 (72) Inventor Johann-Georg Ulrich, Germany, Uisach, Huarkenweg, 22 (72) Inventor Rolf Flech, Germany, Uisach-Frach, Rosenweg, 27 (72) Inventor Fleet Helm Hage Lenzharde, Germany, Germany, 5 (56) References JP-A-60-261911 (JP, A) JP-A-63-230917 (JP, A) JP-A-61-96113 JP, A) JP Akira 60-150409 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) F01L 1/34 F02B 67/06 F16H 7/08

Claims (19)

(57) [Claims] A first camshaft (2) of an internal combustion engine drives a second camshaft (3) by means of a wrapping transmission formed as a chain (4), with respect to the chain (4). Adjustment of the chain (4) by the laterally acting tensioning device (7) changes the relative rotational position of the camshafts (2, 3), which tensioning device (7) adjusts the chain (4). Therefore, the chain (4) slides laterally, and the slack side (6) of the chain (4) becomes longer and the tension side (5) becomes shorter, or the slack side (6) becomes shorter and the tension side becomes longer. Thus, in a tensioning and adjusting device of a wrapping transmission in which a tensioning device is formed, the tensioning device being hydraulically operable, the tensioning device (7) comprises a hollow outer hydraulic piston (8); Hollow inner hydraulic piston guided in this hollow hydraulic piston (9), and a coil compression spring (11) compressed and arranged in a hollow chamber (10) between both hydraulic pistons (8, 9), and the force of the coil compression spring (11) is added. The hydraulic pistons (8, 9) are continually hydraulically biased via the pressure connection (12) between the hydraulic pistons (8, 9) so that the outer hydraulic piston (8) is The hydraulic pistons (8, 9) can be alternately biased by pressure through the pressure passages (23, 25), and the casings (18)
Tensioning and adjusting device, characterized in that it is guided in the interior. 2. The tensioning device (7) has a first pressure connection (1).
2) operated hydraulically via a second pressure connection (2)
2. The device according to claim 1, wherein the device is slidable laterally with respect to the chain via hydraulic pressure. 3. The tensioning device (7) comprises a casing (18).
A first hydraulic piston (9), which runs on the tight side (5) of the chain (4), and a slack side of the chain (4), which is guided in the casing coaxially with this hydraulic piston 6. A hydraulic pump according to claim 1, further comprising a second hydraulic piston for tensioning said first piston, and a first pressure connection between said two hydraulic pistons. An apparatus according to claim 1. 4. In a hollow outer hydraulic piston (8):
Similarly, the hollow inner hydraulic piston (9) is guided, a first pressure connection (12) is arranged in the annular chamber (13) between the two hydraulic pistons (8, 9), and a second Pressure connection (2
4. The device according to claim 3, wherein 1) is externally mounted on one of the two hydraulic pistons (8, 9). 5. The outer hydraulic piston (8) is provided at its end with a collar (16) guided in the casing (18), the second pressure connection (21) being located in the casing (18). And is connected to one end face (16 ') of the collar (16),
5. The device according to claim 4, wherein the third pressure connection is connected to the other end face of the collar in the housing. 6. An end face (16 ') of the collar (16) and an outer hydraulic piston (8) fixed in the casing (18).
Between the coil compression spring (2) and the guide sleeve (19).
6. The device according to claim 5, wherein 0) is arranged in a compressed manner. 7. A coil compression spring (11) is arranged in a compressed state in a central hollow space (10) between the two hydraulic pistons (8, 9). 7. The apparatus according to any one of 6. 8. Three pressure connections (12, 21, 22).
Are connected to three pressure passages (30, 23, 25),
Pump pressure is supplied to this pressure passage from a common main passage (29), the pressure passage (30) for the first pressure connection (12) is directly connected to the main passage (29), and the second and the second. 3
2. The pressure passage (23, 25) is connected to the main passage (29) via an opening (33) controlled to be opened and closed by an adjusting slider (31).
An apparatus according to any one of claims 7 to 10. 9. The adjusting slider (31) has a second or third pressure passage (23, 2) depending on the characteristic quantity of the internal combustion engine.
5) to the main passage (29) so that the electromagnet (3
9. Device according to claim 8, wherein the device can be operated in on-off operation or continuously according to 9). 10. The method according to claim 9, wherein when one of the pressure passages (23 or 25) is biased, the other pressure passage (25 or 23) functions to recirculate the oil without pressure. apparatus. 11. Each of the two pressure passages (23 or 25) is connected to a return passage (26 or 27) via a valve (36) or (37), and the valve (36 or 37) is connected to an adjustment slider (31). Device according to claim 10, characterized in that it can be closed by a valve cylinder (35 or 36). 12. The power supply according to claim 8, wherein the current supply to the electromagnet is varied in proportion to the characteristic quantity of the internal combustion engine in order to continuously slide the adjusting slider. apparatus. 13. A pressure cylinder (35, 3) in which a pressure passage (23, 25) and a recirculation passage (26, 27) are connected to a casing hole (24), and an end side of which is an adjustment slider (31).
13. The device according to claim 1, wherein the adjusting slide is closed and guided in the housing bore by a sealing device. 14. The device according to claim 9, wherein the adjusting slider is operated only by the electromagnet above a temperature of about 40 ° C. of the internal combustion engine. 15. The intake valve camshaft (3) is automatically brought to a relative rotational position during idle running of the internal combustion engine when the adjusting function is defective.
An apparatus according to any one of the preceding claims. 16. The position of the collar (16) is detected by a sensor, the signal of which serves as an adjustment during continuous adjustment and / or serves as a test signal for the function of the tensioning and adjusting device. Claim 1 characterized by the above-mentioned.
The device according to any one of claims 15 to 15. 17. The device as claimed in claim 1, which is for an internal combustion engine having two cylinder rows, in particular a main passage (29), a connecting passage (28),
A control part (4) comprising a valve (36, 37) and an adjusting slider (31) for controlling the valve, comprising an electromagnet (39);
0) is housed in a separate structural part and the pressure passages (2)
3, 25, 30) extend from this structural part to the tensioning and adjusting part (41) provided in the cylinder row, the tensioning and adjusting part comprising both hydraulic pistons (8, 9), the pressure connection (1).
2,21,22) and coil compression springs (11,20)
An apparatus comprising: 18. The device according to claim 1, wherein the tensioning device acts outside the slack side and the tension side of the chain. 19. The device according to claim 18, wherein the tensioning device acts on the chain by tensioning rollers.